1. Field of the Invention
The present invention relates generally to the field of rupturable pressure relief apparatus, and more particularly, but not by way of limitation, to an improved rupturable pressure relief apparatus capable of relieving pressurized fluids in either direction between two pressure zones.
2. Description of the Prior Art
Rupturable pressure relief devices have been developed and used heretofore. Generally, such devices include a rupture disk supported between a pair of supporting members or flanges which are in turn connected to a relief connection in a vessel or system containing pressurized fluid. When the pressure within the vessel or system exceeds the design rupture pressure of the disk, rupture occurs causing pressurized fluids to be relieved from the vessel or system.
Two-way rupturable pressure relief apparatus have also been developed and used heretofore. Examples of such apparatus are described in U.S Pat. Nos. 4,278,181 issued July 14, 1981 to Wood et al. and 4,079,854 issued March 24, 1978 to Shaw et al. Such two-way rupturable pressure relief apparatus are connected between first and second pressure zones, e.g., between a pressure vessel containing a pressurized fluid and the atmosphere, between two vessels containing pressurized fluids at different pressure levels, etc. When the pressure differential exerted on the apparatus in either direction exceeds the pressure differential at which the apparatus is designed to rupture, rupture occurs and pressure is relieved by pressurized fluids flowing through the apparatus from one zone to the other zone.
The most common application of two-way rupturable pressure relief apparatus is where the apparatus protects a vessel or system against overpressure in the normal direction, i.e., from the vessel or system to the atmosphere or to a second vessel or system maintained at a lower pressure, and against excessive vacuum in the reverse direction. The term "normal direction" is used herein to mean the direction through the rupturable pressure relief apparatus whereby a fluid under relatively high pressure is relieved to the atmosphere or other relatively low pressure zone. The term "reverse direction" is used to mean the direction through the apparatus whereby a fluid under relatively low pressure, e.g., air at atmospheric pressure, is relieved to a zone at a lower pressure level, e.g., a vessel under vacuum.
Prior two-way rupturable pressure relief apparatus have been used successfully in applications where the differential between the pressure at which the apparatus must rupture in the normal direction and the pressure at which the apparatus must rupture in the reverse direction is low, e.g., 50 psi in the normal direction and 5 psi in the reverse direction. However, problems have been encountered in the use of prior two-way pressure relief apparatus where the differential between normal and reverse direction rupture is very high, e.g., 150 psi in the normal direction and 3 inches of water column in the reverse direction.
Another problem which has been encountered with prior two-way pressure relief apparatus involves the cleaning of the apparatus. Prior devices have included very fragile parts which are required to obtain rupture at low pressures in the reverse direction and which are difficult to clean without damaging the parts. In the food and beverage processing industry and other industries, the cleaning of rupturable apparatus is best accomplished with the apparatus still installed in its normal operating location. This type of cleaning is referred to as "cleaning in place". Cleaning in place is either impossible or difficult to accomplish with prior two-way rupturable pressure relief apparatus because of the design of the apparatus. Often, the apparatus are formed of a number of parts whereby more than one part surface is exposed to the process media making cleaning difficult and making it possible for substances from the process to collect between overlapping layers, etc. Generally, the prior art devices have had to be removed and taken apart in order to be cleaned and the fragile parts of the devices have had to be replaced each time.
By the present invention, an improved two-way rupturable pressure relief apparatus is provided which is particularly suitable for use in applications where very high pressure differentials between the normal rupture direction and reverse rupture direction are required. In addition, the apparatus of the present invention has a minimum number of parts, the various parts are flat and, other than a structure which includes a large central opening, the surface of only one part is exposed to the process side of the apparatus making the apparatus particularly suitable for being cleaned in place.